Transmission



J. F. SWIFT TRANSMISSION July 22, 1952 Filed May 26, 1948 INVENTOR. OH FSW/FT BYli )a d ATTORNEYS Patented July 22, 1952 I. H TRANSMISSION s John F; Swift, Ypsilanti, Mich., assignor to ma Motor, Company, tion of Delaware Dearborn, Mlch., a corpora- Ap pl ication May 26, 1948, Serial No. 29,388

' This invention relates generally to a transmission and particularly to' a transmission of the type utilizing a fluid pump for supplying fluid under pressure to a control system for the transmission. a r 7 Conventional automatic or semiautomatic transmission for motorvehicles generally utilize a hydraulic system to control the operation of the transmission. Fluidunderpressure is usually supplied to the hydraulic control system by a pair of fluid pumps of any suitable type, one of the pumps being located at the load or tail shaft of the transmission and driven thereby, while the other pumpis located at the input side of the transmission and driven either directly or indirectly by the flywheel of the engine. The load shaft pump "is necessary'to enable fluid pressure to be supplied when'the vehicle is coasting and also whenthe engine is stalled and itis necessary tostart the engine by pushing thecar. yThe front pump is alsoessential, since duringidling and low-speed conditionsf-the' load shaft pump will not furnish sufiicient fluid under, ressure to operate the hydraulic control system. Although one pump would have suflicient capacity for the system, two must thus be employed, resulting in an unnecessary loss of power and'torque during normal operating conditions. j J

It is accordingly an object of the present invention to provide a transmission in which a pump is located between ajdriving and'a driven member of the transmissionjand is operated by thespeed differential existing between the driving and driven members, The'arrangement is such thatthe output ofthe pump. is proportionate'to'the differential speed between the driving and driven members and progressively decreases as the speeds of the driving and driven members become equalized. An arrangement of this type is particularly advantageouswhen employed in a transmission vutilizing "a hydraulic torque transmitting devicefsuch as a fluid coupling or a torque converter. In the case of a torque converter, for example, the differential pump may be connected between the converter impeller and the converter turbine. Inasmuch as the impeller is driven by, the input shaft or engine flywheel and the turbine is connected to the load-or output shaft of the transmission, it will be seen that a maximum .diiferential speed exists between the impeller and turbine during idling, and that as the vehicle speed increases the speed of the tiubine' will progressively approach the speed of the impeller and the. output v warmsbe r duall red ce unt it 4 Claims. (01. 74-732) 2 reaches a minimum during normal operation of the transmission. At this time, the speeds of the impeller and turbine are substantiallyequal, and consequently the pump is practically inoperative. Another object of the present invention is'to provide a transmission employing a difierential pump in combination with a second pump, the output of the differential pump being at its maximum during idling andgradually decreasing while the output of the second pump is a minimum during idling and gradually increases. Sufficient fluid under pressure isthus supplied to the hydraulic control system of the transmission at all times, both during idling and low speeds and also under high speed conditions yet full operation of two pumps is avoided. This results in a power saving and also prolongs the life'of the differential pump. Normally, there is a torque reaction loss in a fluid pump" used in a transmission since the reaction is taken by the housing, but in the differentialpump utilized in the present transmission the torque reaction is taken by a driven member inthe transmission and is thus utilized to assist in driving the vehicle; wheels, and this power loss is thus avoided.

Still another object of the invention is to provide automatically operated means for imparting sufiicient drag or reaction in the system to insure operation of the pump when starting the engine or during idling, provision 'being made for automatically'releasing this drag when it is no longer necessary so that it will not be present during normal operation conditions; 9 v

A further object of the invention is to provide a transmission having a hydraulic torque transmitting device, the fluid chamber of which is expansible, under pressure so that it'may act'as a fluid accumulator holding an excess of fluid under pressure which may be instantaneously supplied to the fluid pressure control system of the transmission when necessary to apply brake or clutch actuating means. This eliminates the time lagin operation of the actuating. devices which might otherwise occur due to the time necessary for the fluid pump to supply sufficient fluid to actuate the devices. This maybe accomplished by providing for movement of one or more of the walls of the hydraulic torque transmitting device under the action of fluid pressure supplied by a hydraulic pump. The output of the pump, may for example, be passed through the hydraulic torque transmitting device and then into the hydraulic control system.

Other objects and advantages 'of the present invention will be made more apparent as -this Figure 2 is .an enlarged cross sectional View through a portion of the transmission shown in Figure 1, illustrating the torque converter and the differential pump thereof.

Figure 3 is a fragmentary cross sectional view of the mechanism utilized to automatically apply drag in the transmission during idling.

Figure 4 is a cross section through the pump taken on the line 44 of Figure 2; a I

While it will be understood that the present invention may be employed in various types of transmissions, for the purpose of; illustration. there is shown diagrammatically in Figure l a three-speed automatic transmission of the planetary type employing a torque converter and in which he yarious control devices of, the trans-. mis ionarehydraul eally actuated .Th tranemiesim s heusedwithina casing H... I

andhasadr ve shaft-indent d to be co nected ta he-crank. s aft f the. ve i le en ine (not hewnhan i t rm ia shaft l3. a d aload ha 4 a ap d. to be enneeted the ea zi-led veme ns f t e c e Th t en m seien inc ud s aad fie nfi a .1 mp;. and-a e haf P i 8. The shaft I3 is driven through the torque converter l6 from thedriveshait I2 in a manet to hed se i e .mor i de l: ter. 7 and the intermediate shaft i3 is adapted to be connected to a clutch carrier |.9;by a second speed clutchj l. The clutch carrier is is also adapted to be oc d, to ah eeet t rrie 2.2, means r h e p ed iuenee ,Thefe eee c m ra seated ma p tth a .ihe i meeiaesh a i d. carries I clusters of planet pinions 2 d, '26, and 21.

Planet; pinions MQmes'h with ia sun gear I 2 8 cares: y t ie hee e; dines a i n 26n'1eshwith a sun gear 2 9,mountedupon the.

intermediate shaft 13,; and planet pinion 2"! with the sun; gear? 3| carried byi; the load shaft Id; Inorder' to transmit torque through the multiple planetary gearing system in the forward direction, an overrunningclutch' 32 is connected to. the planet carrierZ-Z, The overrunning clutch 32, is selctively connected to. the. transmission casingby means of the forwardspeed brake. 33.

The brake 33 is ac'tuated' by.the hydraulie c'ylir der.34 and piston 36. 1 I I y r i To condition the transmission to transmit torque in the revers direction; reversef'sp'eed brake mechanismiffis providedto selectively lock the clut :h carrier l9fto the transmission casing. Thefreverse speed brake is adapted to be" actuated by the hydraulic cylinder 38 and piston 39. The forward and reverse speed cylinders 34 and 38 respectively are supplied with fluid from a fluid conduit 4| innerconnecting the cylinders and the pumps I! and I8;

'Thesecond'and third speed clutches 2| and 23 are actuated; by. pistons 42 and d3 housed within cylinders 44 and 45' respectively, and fluid under pressure for 7 operating the clutches is supplied from the load shaft pump 18 through a conduit 41 to a sleeve valve 48 controlled by a centrifugal governor. 49. From the sleeve thefluid' is distributed to the cylinders Mend 45 through conduits 5 l' and 52* respectively.

By selective operation of" the forward speed brake 33,the second speed clutch 21, thethird speed clutch 33; and'the reverse speed brake 3T torque converter ,of-theflexible disk 53 is also connected to the peripheries of an inner shroud 59 and an outer shroud 51,.the latter cooperating with the former to form; a rotatingfluid chamber housing for torque converter It: At its inner edge the inner shroud 56 is formed with a forwardly extending axial flange 58 keyed to a hub 59 to permit axial sliding movement of the flange 58 upon the hub. A sheet metalj'cap 6| encircles the anula flang 58 a e ecepi al vr ce d.a ilo d w h n-ana n la ereqve- 62 rm d t the rearward end of the drive shaft. 12.

, Itwill be noted that intermediate their inner and outer portions, the flexible disk 53 and inner hre d 5 ares ed f mee h th r 'anda tabl 1 Hea ed oreentout e pre nt-ben ing stresses in the crankshaft from beingtransmitted to the torque converter.

The radially inner edge-ofithe outer shroud 51 of .the torque converter carries a hub .62 which is piloted upon an annular'flang e-Giipf the trans: mission housing I l. A seal 6.4,is provided betw en the hub. 62 and the casing. 'Itwill bev'appa ient. that the outershroud 57 0f" the torque. converter maybe flexed axially reaf ardly. by the fluid pressure within the torque'converter, the hub 62.

at theradially inner edge offthe shroud being adaptedtov slide axiallyupon thelannular flange 63 6f theica'sin'g. The torque converter is conven tionally providedwith aniimp'eller 66 carriedby the outer shroud 57, a turb" ,efSjl and. areactor' B8. The reactor 68 is connected j through an OVEI'r', running brake69 to'tl'ie forwardly extending por tier; of the annular flange 6. .of the 'transmiss'ion ca in -1 v 1 The turbine, 5.1" isfmounted up on ajhub, ll which in turn is secured to thehousi g' ,;l2..ofj the differ-v ential fluid pump 11.? Althoug'hvarioustypes, of

fluid pumps can be used with the present inven-. tion, the pump [1 is a conventional, pump of the ong ar o rotor the internal rotor. The hub "59; i s ,connectedto e axi fl e he; nn ri hmu fi and forms the driving element offthe pump. A Inas much as the inner shroud; 56' is connected by 1 means. of the outer shroud i'fli to the impellertfi; I

it will be seen that the differentialpump l1 is-directly connectedbetween-thf: impeller 6t and lth e turbine 61. During idling when the vehicle is;

statiqnary. the turbinie 61; which is connected to the intermediate shaft! 3-jof the; transmission Jby the hub] I, is stationary, anda maximum differ en ia sp e is ain betwe nthe t e lem n of heump. n ,ompn. ru e u eis th e:

forejat a maximumfAs'th e vehicle begins to evea s its 8 ed, the l eed ft e.

a l-v increases nd rpre'eeh s he. t ed-J ff he. impeller 66. At the same;time; thediiierential;

speed between thetiiioelements of the pump de- .eearor rem? vingqne e s o tb. wi h. he aide ofthe'pinion rotor being offset from the axis of creases and the output of the pump is accordingly decreased. When normal operating'conditions are reached, the speed of the turbine is substantially that of the speed of the impeller, and the two elements of the pump areaccordingly rotating at substantially the same speed. The output of the differential pump I1 is therefore practically nil.

The input of the nicates with the transmission sump through conduit 16 in the pump housing 12, conduit 11; in the intermediate shaft l3, conduit I8 in the transmission casing I I,'and tube .19. The pressure chamber 8| of the differential pump I'I communicates through a, conduit 82 in the pump housing 12 with the interior of the torqueconverter I6,

through the space between thev turbine 6'! .and.

reactor 68. A fluid outlet is provided between the impeller 66 and thereactor and communicates through a conduit 83in the annular hub 63 of the casing to the supply conduit 4|, Figure 1. Fluid under pressure is thus supplied to the hydraulic control system from the pressure chamber 81 of the differential pump II afterflrst being transmitted through the torque converter I6. Inas-. much as the supply conduit is also connected to the pressure chamber 84 of the load shaft pump I8, it'will be seen that the two pumps are innerconnected and each supplies fluid pressure to the entire hydraulic system.

Provision is made for limiting the pressure in the system to a predetermined value. The pressure side of the differential pump communicates through a passage 85in thepump housing and ports 86 and 81 in the hub 59 and'intermediate shaft I3 respectively to the central bore 88 of the intermediate shaft. A relief valve 89 is slidably the faces will result in moving the valve against the action of the spring 9| when a certain predetermined pressure has been reached, to open theexhaust port 92 and by-pass the fluid pressure from the pressure-chamber 8I of the pump to the conduit TI and thence to the transmission sump. i. 7

Reference is now made to Figure 3. A friction shoe 96 is carried at the outer end of a plunger 91 which in turn is threaded into a piston 98 slidably mounted in a cylinder 99 supported upon a bracket I68 carried by the transmission casing II. and plunger 91 radially inwardly toward the periphery of the exterior surface of the clutch carrier I9. The resulting frictional engagement between the .clutch carrier and the friction shoe 96 carried by the plunger 91 imparts suflicient drag to the clutch carrier to enable the differential pump I! to operate even though the transmission ay be in n ut a I The cylinder 98 is connected by a conduit (not shown) to the cylinder 34 for the forward speed brake 33 so that the friction shoe 96 will beautomatically released when the forward speed brake 33 is engaged. It will thus be seen that the device functions only for a short interval of time and unnecessary wear is prevented. With this arrangement, even though the transmission is left in neutral when the vehicle is stopped, sufficient resistance to rotation of the converter turbine and its innerconnected mechanism is provided so that the differential pump will function and will supdilferential pump I'I commu A spring llll'normally urges thepiston 98 v ply fluid under pressure to the hydraulicactuating system, enabling the various controls tobe operated.

From the foregoing description it will be seen that the differential pump II, which is connected between the impeller and turbine of thetorque converter, supplies sufficient fluid under pressure to the hydraulic control system during idling and low vehicle speeds to permit the actuation of the various hydraulic controls. As the vehicle speed increases and the load shaft pump I8 becomes operative and supplies fluid pressure to the system, operation ofthe differential pump I1 is no longer necessary, and its output is automatically and progressively decreased until it is substantially eliminated. As a result, a'saving' in power is effected since during normal operation only one pump need be operated instead of the usual two. Injaddition, when the differential pump I1 is in operation, its torque reaction is taken by the turbine and the intermediate shaft and thus is uti-. lized in supplyingpower to the vehicle wheelsh This distinguishes from the normal pump operation in which the reaction is taken by the housing and thus is not used. It has been found that a transmission embodying thepresent invention is the equivalent of one with the conventional pump installation at low car speed and is considerably superior at speeds above 15 miles per hour. A saving of approximately 50% of the power normally used in driving the fluid pumps is efiected, and yet suflicient fluid is provided for all hydraulic control functions.

In addition, the torque converter functions as an accumulator. The fluid chamber formed between the inner and outer shrouds 56 and 51 respectively is expansible under the action of fluid pressure. As previously noted, the inner shroud 56 is somewhat flexible, and in addition the radially inner ends of each of the shrouds are axially slidable. As a result, the volume of the chamber is increased under the action of fluid pressure. The fluid supplied by the differential pump I! is introduced into the torque converter, and being under considerable pressure results in an expansion of the chamber. An additional supply of fluid under pressure is thus made'available for instantaneous application of the various hydraulic actuating devices of the transmission. For example, operation of the valve I02 for the reverse speed cylinder 38, the valve I03 for the forward speed cylinder 34, or the sleeve valve 48 forthe second and third speed clutches 2| and 23 respectively, calls for an immediate supply of fluid to the particular cylinder and piston to apply the adjacent clutch or brake. While this can be supplied by the pumps, a time lag results due to the inability of the pumps to supply a suflicient quantity of fluid instantaneously. The expanded shrouds 56 and 51 of the torque converter, however, can immediately return to their normal position when this additional fluid is demanded, and an additional amount of fluid is thus available to immediately apply the particular actuating means. It will be noted, of course, that the entire hydraulic system is interconnected, so that the torque converter functions as an accumulator at all times, regardless of whether or not the front differential pump I1 is in operation. In other words, the fluid pressure from the rear pump is also effective to expand the hydraulic chamber of the torque converter so that it may function as an accumulator.

From the foregoing it will be seen that I have provided a transmission which is no more complicated nor expensiveto huild than the conven tional transmission o'i thi's-type, yet whihresults in a greater power and torque output 'd'uato' theelimination of powerlosses andwhich al'sois adapted to function: in a more effective and efficient' manner. a V a Although I haveshown and described certain embodiments of theinvention, it: willbe understood that I do 'not wish to-belimited-t'o" the exact construction shown and described, but that various changes andmodifications may be made without departing from; the spirit andscope of my invention, as defined in theappended claims. L

What is claimed is:

l. Ina transmission having a casing: and d'rive and load shafts; sheet "'metal' drive disk se cured to one end of said-drive shaft, a flexible sheet metal shroud'spaced from saiddrive -disk;

and seoure'd adjacentits periphery to said drive disk, a hub for said shroudtel'escopically and sl-idab'ly received within"a're'cessformedin the above-mentioned end of saiddrive shaft, a second flexible sheet meta-l shroud secured at its pe riphery to said drive disk and said-first-shroud, said second shrouded-operating-With said first shroud to form a fluid chamber; an impeller in said fluid chamber mounted upon said" second shroud, aturbinein said fluid chambermounted upon said load shaft, a;hub-fo rsaid second shroud telescopically 'andnslidab-ly co-operati-ng with a portion of saidtransmission casing, a fluid seal between said last-mentioned ,hub' and said casing,-said shrouds'and'hubs being'movable axially-outwardlyunder thekaction" cf the fluid pressure in said fluid chamber't'o increase-the volume thereofiand form-an accumulator for' the storage ofadditional fluid under pressure.

2. In a variablespeed power transmission, in combination, a casing; a drive shaft, an interemediate shaft and'a load; shaft; a hydraulic torque converter having an; impeller driven by said drive shaft; 'a turbine directly connected to said intermediate shaft to drive? the latter at a,1l ratio'and a reactor connected toisaid casing," gearing, between saidinterm'edi'ate" and load shafts for transmitting power'therebetween: at a: plurality of difierent'speed ratios, hydrau1ic= ally actuated" control, means-,associatedwith said. gearing for. effecting saidspeed ratios; a fluidpump havinga' pair'of' coactinge'lements; one of said elements being connected tosaid-converter impeller: and-the" other ofsaid: ele ents being connected to said converter turbine; at coniduit leading fromthe: output. of saidipump' to' the interior of said torqu'e' converter, a: second conduit leading from the'interiorgofsaidtorque. converter to said hydraulically actuated control means to supply fluid'under pressure to actuate the latter, theoutput of said pump'varyingfii rectly as the relative 'speed between said impeller and'turbine; I

3. In a transmission having a" casing-and'driveand load shafts, a driving .member, aflexible sheet metal shroud securedadjacent itsperiphery tothe driving member and having its" hub mounted for slidingfimovement'in an-axial dio 32 rection', a: second sheet metal shroudi connected at its-periphery to said drivin'g member and: to said first shroud and having a-hub mounted for slidingmovement in 7 an axial; direction and coop'erati'ng with said first shroud to form a fluid chamber, animpeller in said fluid chamber mounted uponsaid second shroud, aturbine in said fluid chamber connected to said load shaft, said shroudsand hubs beingmovable axially outwardlyunder" the actionof: the fluid pressure in said fl'ui'd chamber" to increase thenvohime thereof and form an accumulator for the storage of'additional-fiuid under pressure.

4'. In a variable speedfltransmission for; a motorvehicle, in: combination; aihousing, a drive shaft,- a torque: converter impeller: driven byv said drive shaft a driven shaft', a torque' converter'turbine directly connecteditoisaid driven shaft; arload' shaft, varia'ble speed gearingibetween said driven and load shaftsior.transmitting power to said load-shaft: at a plurality-of: different speed ratios, hydraulically actuated 'Icontrol devices associated with said: gearing tor-effecting fsaid speed ratios, a pair of 'fluid'delivery pumps, conduits intere connecting the outputs, of said two pumps to" provide. alcornmondelivery circuit, conduits: connecting said common delivery "circuit to said hydraulically; actuate'di controlri devices, one of said pumps having; a' .housing;,mounted upon the transmission housing; and arotorxin' the pump. housing: driven? by' s'aict load; shaft sothat the outputhof said? 'pumpi' is- -zeroz= when the" vehicle is: stationary and progressively increases as the vehiclespeed increases; thelotherof. said pumps having achousing operatively connectedto said torque converter: turbine and: a rotor operatively;

connected. to. said torque converter: impeller so that the output .ofisaid' second pump is at1a maximum: when the vehicle is. stationary and. the first pump;, isinoperative" and decreases progressively asethes speed differential between said torque converterfimpeller and turbine decreases tomaintaini'operating: pressure inf. thecommon fluid, delivery circuitunder all conditions, saidcsecond fluid pumpibeingg substantially inoperative under normal vehicle speed operation in: high speed ratio to minimize the'power' loss duezto pump operation;

J OHN F.

e H REFERENCES CITED The following references are of recordin 'the file ofthis pa-tent:

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